bug: ANR crash java.util.ConcurrentModificationException com.getcapacitor.Plugin.notifyListeners

[Rosadojonathan]

Bug Report

Capacitor Version

  @capacitor/cli 1.5.2

  @capacitor/android 2.4.7

  @capacitor/ios 2.4.7

  @capacitor/core 1.5.2

Platform(s)

Android

Current Behavior

My app seems to crash fairly often (4.5% of sessions) on android.
It seems to happen after accessing the Camera, but not while accessing it.
The error I see mentioned on the Google Play Console ANR crash report.

java.util.ConcurrentModificationException
com.getcapacitor.Plugin.notifyListeners

Expected Behavior

I expect the app not to crash as often.

[danishin]

I have the same issue and in my case, it seems to happen in push-notifications library.
We also have fairly high number of crashes happening with our users.
I'm currently using "@capacitor/android": "3.0.2", "@capacitor/ios": "3.0.2", "@capacitor/push-notifications": "1.0.2"

java.util.ConcurrentModificationException
	at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:573)
	at com.getcapacitor.Plugin.notifyListeners(Plugin.java:671)
	at com.capacitorjs.plugins.pushnotifications.PushNotificationsPlugin.sendToken(PushNotificationsPlugin.java:194)
	at com.capacitorjs.plugins.pushnotifications.PushNotificationsPlugin$1.onSuccess(PushNotificationsPlugin.java:91)
	at com.capacitorjs.plugins.pushnotifications.PushNotificationsPlugin$1.onSuccess(PushNotificationsPlugin.java:88)
	at com.google.android.gms.tasks.zzn.run(com.google.android.gms:play-services-tasks@@17.2.0:4)
	at android.os.Handler.handleCallback(Handler.java:739)
	at android.os.Handler.dispatchMessage(Handler.java:95)
	at android.os.Looper.loop(Looper.java:135)
	at android.app.ActivityThread.main(ActivityThread.java:5927)
	at java.lang.reflect.Method.invoke(Native Method)
	at java.lang.reflect.Method.invoke(Method.java:372)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)

[phal0r]

Can confirm this error on Android. In my case it's the Keyboard plugin:

java.util.ConcurrentModificationException: 
  at java.util.ArrayList$Itr.next (ArrayList.java:860)
  at com.getcapacitor.Plugin.notifyListeners (Plugin.java:348)
  at com.getcapacitor.Plugin.notifyListeners (Plugin.java:361)
  at com.getcapacitor.plugin.Keyboard.access$900 (Keyboard.java:25)
  at com.getcapacitor.plugin.Keyboard$1$1.onGlobalLayout (Keyboard.java:91)
  at android.view.ViewTreeObserver.dispatchOnGlobalLayout (ViewTreeObserver.java:1056)
  at android.view.ViewRootImpl.performTraversals (ViewRootImpl.java:2739)
  at android.view.ViewRootImpl.doTraversal (ViewRootImpl.java:1819)
  at android.view.ViewRootImpl$TraversalRunnable.run (ViewRootImpl.java:7781)
  at android.view.Choreographer$CallbackRecord.run (Choreographer.java:1031)
  at android.view.Choreographer.doCallbacks (Choreographer.java:854)
  at android.view.Choreographer.doFrame (Choreographer.java:789)
  at android.view.Choreographer$FrameDisplayEventReceiver.run (Choreographer.java:1016)
  at android.os.Handler.handleCallback (Handler.java:883)
  at android.os.Handler.dispatchMessage (Handler.java:100)
  at android.os.Looper.loop (Looper.java:224)
  at android.app.ActivityThread.main (ActivityThread.java:7562)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:539)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:950)

The error suggests, that the cause is in the BasePlugin Class and not a plugin itself. Looking at the sourcecode I am not sure, how notifyListeners modifies its list as it actually only reads from it. Hopefully someone from the core team can shed some light on this.

[ionitron-bot]

Thanks for the issue! This issue is being locked to prevent comments that are not relevant to the original issue. If this is still an issue with the latest version of Capacitor, please create a new issue and ensure the template is fully filled out.